This grant is submitted in response to RFA:DK-03-006 "Bariatric Surgery Clinical Research Consortium". We are making application to be one of the interactive Clinical Centers in this Consortium. Our research group has had a longstanding interest in eating disorders and eating problems, and has recently been interested in research in binge eating disorder, obesity and bariatric surgery. As noted in the RFA, obesity has become an alarmingly common problem in America, and baritaric surgery procedures appear to be the treatment of choice for patients with severe obesity. However, a number of important research questions have yet to be answered. In this application we review various areas of research including the relationship between psychopathology and outcome of bariatric surgery, particularly as it relates to binge eating and binge eating disorder, the development of eating disorders as a consequence of bariatric surgery, the psychosocial outcomes of individuals undergoing bariatric surgery, psychosocial interventions for patients undergoing bariatric surgery, and peptides and feeding in bariatric surgery. Preliminary data are included detailing our experiences in working with this population including an ongoing project collecting standardized databases on patients undergoing bariatric surgery at various sites, two follow-up studies that have been completed status post-gastric bypass, and our experience with various modalities which could be helpful to the consortium. These include ecological momentary assessment paradigms, the use of structured and self-report instruments, the assessment of quality of life and studies of eating behavior and peptides in our human feeding laboratory. We propose two experiments. The first is a short-term study examining eating behavior both pre- and post-bariatric surgery using 72 hour dietary recall, ecological momentary assessment and feeding laboratory assessment over a period of 9 months. A second longer-term study would involve a 24 month prospective longitudinal design with a careful assessment of psychopathology and various behavioral variables that might impact on response to surgery, on the amount of weight loss, the amount of weight regained, and on psychosocial complications post operatively, as well as quality of life. Specific hypotheses are offered regarding both of these experiments.